1. Field of the Invention
The present invention relates to a disk array apparatus, particularly to a magnetic or optical type disk array apparatus.
2. Background of the Invention
The disk array apparatus in which many magnetic or optical type disk drives are incorporated into a casing is connected to a dedicated high-speed network line such as an optical network line, and is managed by management software. The disk array apparatus is used as SAN (Storage Area Network), NAS (Network Attached Storage), or a single RAID (Redundant Array of Inexpensive Disks) disk apparatus.
Japanese Patent Application Laid-Open No. 9-274791 discloses an example of such kind of disk array apparatus. In the disk array apparatus disclosed in Japanese Patent Application Laid-Open No. 9-274791, a board is used on which a disk drive and a control circuit are mounted on the same plane and an air guide plate is provided on this board so that cooling flow passages for the disk drive and control circuit are separated. Japanese Patent Application Laid-Open No. 2001-338486 also discloses a disk array apparatus in which a flow passage including the disk drive and a flow passage including the control board are separated to evenly cool each of the passages.
Japanese Patent Application Laid-Open No. 5-54626 discloses a disk drive apparatus in which the disk drives are arranged in a staggered array. Japanese Patent Application Laid-Open No. 2001-344961 discloses a magnetic type disk drive in which a cooling control plate is provided to increase a wind velocity of a cooling air passing through the printed circuit board side. Japanese Patent Application Laid-Open No. 5-175679 discloses a technique in which an impingement jet duct is provided in an electronic device so that air impinges directly on a heating body by the impingement jet air duct.
In the disk drive apparatus disclosed in Japanese Patent Application Laid-Open No. 9-274791, the number of mountable disk drives is restricted because the disk drive and the controller are mounted on the same board. There is no sufficient consideration for equalization of a temperature distribution among the disk drives mounted on the board. In the disk drive apparatus disclosed in Japanese Patent Application Laid-Open No. 2001-338486, it is described that the whole of the disk drive apparatus is cooled to the same level as other components. However, because the disk drive and the controller are placed on the same board, there is no consideration for the equalization of the temperature distribution among the disk drives in the cooling air flow direction, when the plural disk drives are mounted.
In the disk drive apparatus disclosed in Japanese Patent Application Laid-Open No. 5-54626, although flow resistance is increased, mixing of cooling air flowing along side faces of the disk drives is enhanced, which allows improvement of cooling capacity for the disk drive. However, a large space is formed above the disk drive in the case where the many disk drives are arranged in the cooling passage, the cooling air may flow through the space above the disk drive without passing through the disk drive arranged near the board surface in a staggered array in which the flow resistance is large.
In the disk drive apparatus disclosed in Japanese Patent Application Laid-Open No. 2001-344961, the cooling capacity can be improved for the single disk drive. However, the disk drive apparatus disclosed in Japanese Patent Application Laid-Open No. 2001-344961 has a single disk drive, and there is no consideration for the case that the many disk drives are arrayed. In the electronic apparatus disclosed in Japanese Patent Application Laid-Open No. 5-175679, because air impinges directly on each of heating bodies, the temperature distribution can be equalized among the disk drives. However, in order to obtain the good cooling capacity, it is necessary that the impingement jet air duct and a fan provided in the jet air duct should be provided at the most upstream side of the cooling air in the casing. In the electronic device, it is possible that the air duct and the fan can be provided at this position. On the contrary, in the disk array apparatus, it is difficult to take such a layout because the disk drives are arranged on the most upstream side of the cooling air. Additionally, in order to evenly blow the cooling air to each of the disk drives, the flow resistance is extremely increased in an opening provided in the impingement jet air duct, which results in the upsizing of the fan provided in the impingement jet air duct.